This guide teaches you how to swap a single-pole light switch and a standard duplex outlet the way a careful pro would. It opens with safety habits: cut power at the breaker, tag it, and verify zero volts with both a non-contact tester and a multimeter. You map your circuit by labeling hot, neutral, and ground, check box-fill, and prep pigtails so only one conductor lands under each device screw. Chapter 1 sets the groundwork: tools, parts, wire gauges, device ratings, and how to document wiring with photos before you touch anything. Chapter 2 walks the replacements step by step—removing back-stabbed connections, forming clockwise hooks, using pigtails for pass-throughs, aligning devices flush, and powering up to confirm correct voltage hot-to-neutral and hot-to-ground, plus a brief heat check. It also explains GFCI basics and how to handle a half-switched receptacle. Chapter 3 is your troubleshooting playbook: fix reverse polarity, open ground, open neutral, and dangerous bootleg grounds; spot signs of shared neutrals or multi-wire branch circuits; and know when to stop and call a licensed electrician. A simple maintenance plan—periodic tests and updated breaker labels—keeps future work safer and faster.